Fault diagnostic systems and methods for model predictive control

ABSTRACT

A model predictive control (MPC) module: identifies sets of possible target values based on an engine torque request; determines predicted operating parameters for the sets of possible target values, respectively; determines cost values for the sets of possible target values, respectively; selects one of the sets of possible target values based on the cost values; and sets target values based on the possible target values of the selected one of the sets. An actuator module controls an engine actuator based on one of the target values. A fault diagnostic module selectively diagnoses a fault in the MPC module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.14/225,502 filed on Mar. 26, 2014, Ser. No. 14/225,516 filed on Mar. 26,2014, Ser. No. 14/225,569 filed on Mar. 26, 2014, Ser. No. 14/225,626filed on Mar. 26, 2014, Ser. No. 14/225,817 filed on Mar. 26, 2014, Ser.No. 14/225,896 filed on Mar. 26, 2014, Ser. No. 14/225,531 filed on Mar.26, 2014, Ser. No. 14/225,507 filed on Mar. 26, 2014, Ser. No.14/225,808 filed on Mar. 26, 2014, Ser. No. 14/225,587 filed on Mar. 26,2014, Ser. No. 14/225,492 filed on Mar. 26, 2014, Ser. No. 14/226,006filed on Mar. 26, 2014, Ser. No. 14/225,496 filed on Mar. 26, 2014, Ser.No. 14/225,891 filed on Mar. 26, 2014. The entire disclosure of theabove applications are incorporated herein by reference.

FIELD

The present disclosure relates to internal combustion engines and moreparticularly to engine control systems and methods for vehicles.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

Internal combustion engines combust an air and fuel mixture withincylinders to drive pistons, which produces drive torque. Air flow intothe engine is regulated via a throttle. More specifically, the throttleadjusts throttle area, which increases or decreases air flow into theengine. As the throttle area increases, the air flow into the engineincreases. A fuel control system adjusts the rate that fuel is injectedto provide a desired air/fuel mixture to the cylinders and/or to achievea desired torque output. Increasing the amount of air and fuel providedto the cylinders increases the torque output of the engine.

In spark-ignition engines, spark initiates combustion of an air/fuelmixture provided to the cylinders. In compression-ignition engines,compression in the cylinders combusts the air/fuel mixture provided tothe cylinders. Spark timing and air flow may be the primary mechanismsfor adjusting the torque output of spark-ignition engines, while fuelflow may be the primary mechanism for adjusting the torque output ofcompression-ignition engines.

Engine control systems have been developed to control engine outputtorque to achieve a desired torque. Traditional engine control systems,however, do not control the engine output torque as accurately asdesired. Further, traditional engine control systems do not provide arapid response to control signals or coordinate engine torque controlamong various devices that affect the engine output torque.

SUMMARY

In a feature, an engine control system is disclosed. A model predictivecontrol (MPC) module: identifies sets of possible target values based onan engine torque request; determines predicted operating parameters forthe sets of possible target values, respectively; determines cost valuesfor the sets of possible target values, respectively; selects one of thesets of possible target values based on the cost values; and sets targetvalues based on the possible target values of the selected one of thesets. An actuator module controls an engine actuator based on one of thetarget values. A fault diagnostic module selectively diagnoses a faultin the MPC module.

In future features, the MPC module selects one of the sets of possibletarget values further based on predetermined ranges for the targetvalues, respectively.

In still further features, the fault diagnostic module diagnoses thefault when one of the target values is outside of its predeterminedrange.

In yet further features, the MPC module: identifies a first one of thesets of possible target values based on a first cost value of the firstone of the sets; determines whether the possible target values of thefirst one of the possible sets are within the predetermined ranges,respectively; when one of the possible target values of the selected oneof the sets is outside of its predetermined range, identifies a secondone of the sets of possible target values based on a second cost valueof the second one of the sets; and, when the possible target values ofthe second one of the sets are within the predetermined ranges,respectively, selects the second one of the sets.

In further features, the fault diagnostic module diagnoses the faultwhen the second cost value of the second one of the sets is less thanthe first cost value of the first one of the sets.

In still further features, the fault diagnostic module diagnoses thefault in the MPC module when the MPC module fails to select one of thesets of possible target values within a predetermined period.

In yet further features, the MPC module further determines an integratorvalue based on a difference between a first one of the predictedoperating parameters and one of a measured and an estimated value ofthat operating parameter.

In further features, the fault diagnostic module diagnoses the fault inthe MPC module when the integrator value is greater than a predeterminedvalue.

In still further features: a reference module determines referencevalues based on the engine torque request; and, when the fault isdiagnosed in the MPC module, the actuator module controls the engineactuator based on one of the reference values.

In still further features: a boost actuator module that controls openingof a wastegate of a turbocharger based on a second one of the targetvalues; an exhaust gas recirculation (EGR) actuator module that controlsopening of an EGR valve based on a third one of the target values; and aphaser actuator module that controls intake and exhaust valve phasingbased on fourth and fifth ones of the target values, respectively,wherein the actuator module controls the opening of a throttle valvebased on the one of the target values.

An engine control method for a vehicle includes, using a modelpredictive control (MPC) module: identifying sets of possible targetvalues based on an engine torque request; determining predictedoperating parameters for the sets of possible target values,respectively; determining cost values for the sets of possible targetvalues, respectively; selecting one of the sets of possible targetvalues based on the cost values; and setting target values based on thepossible target values of the selected one of the sets. The enginecontrol method further includes: controlling an engine actuator based onone of the target values; and selectively diagnosing a fault in the MPCmodule.

In further features, the engine control method further includesselecting one of the sets of possible target values further based onpredetermined ranges for the target values, respectively.

In still further features, the engine control method further includesdiagnosing the fault when one of the target values is outside of itspredetermined range.

In yet further features, the engine control method further includes,using the MPC module: identifying a first one of the sets of possibletarget values based on a first cost value of the first one of the sets;determining whether the possible target values of the first one of thepossible sets are within the predetermined ranges, respectively; whenone of the possible target values of the selected one of the sets isoutside of its predetermined range, identifying a second one of the setsof possible target values based on a second cost value of the second oneof the sets; and, when the possible target values of the second one ofthe sets are within the predetermined ranges, respectively, selectingthe second one of the sets.

In further features, the engine control method further includesdiagnosing the fault when the second cost value of the second one of thesets is less than the first cost value of the first one of the sets.

In still further features, the engine control method further includesdiagnosing the fault in the MPC module when the MPC module fails toselect one of the sets of possible target values within a predeterminedperiod.

In yet further features, the engine control method further includesdetermining an integrator value based on a difference between a firstone of the predicted operating parameters and one of a measured and anestimated value of that operating parameter.

In further features, the engine control method further includesdiagnosing the fault in the MPC module when the integrator value isgreater than a predetermined value.

In still further features, the engine control method further includes:determining reference values based on the engine torque request; and,when the fault is diagnosed in the MPC module, controlling the engineactuator based on one of the reference values.

In yet further features, the engine control method further includes:controlling opening of a wastegate of a turbocharger based on a secondone of the target values; controlling opening of an exhaust gasrecirculation (EGR) valve based on a third one of the target values; andcontrolling intake and exhaust valve phasing based on fourth and fifthones of the target values, respectively, wherein the engine actuator isa throttle valve.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example engine systemaccording to the present disclosure;

FIG. 2 is a functional block diagram of an example engine control systemaccording to the present disclosure;

FIG. 3 is a functional block diagram of an example air control moduleaccording to the present disclosure;

FIG. 4 is a flowchart depicting an example method of controlling athrottle valve, intake and exhaust valve phasing, a wastegate, and anexhaust gas recirculation (EGR) valve using model predictive controlaccording to the present disclosure;

FIG. 5 is a flowchart depicting an example method of diagnosing faultsin a model predictive control module according to the presentdisclosure; and

FIG. 6 is a flowchart depicting an example method of testing a modelpredictive control module according to the present disclosure.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

An engine control module (ECM) controls torque output of an engine. Morespecifically, the ECM controls actuators of the engine based on targetvalues, respectively, based on a requested amount of torque. Forexample, the ECM controls intake and exhaust camshaft phasing based ontarget intake and exhaust phaser angles, a throttle valve based on atarget throttle opening, an exhaust gas recirculation (EGR) valve basedon a target EGR opening, and a wastegate of a turbocharger based on atarget wastegate duty cycle.

The ECM could determine the target values individually using multiplesingle input single output (SISO) controllers, such as proportionalintegral derivative (PID) controllers. However, when multiple SISOcontrollers are used, the target values may be set to maintain systemstability at the expense of possible fuel consumption decreases.Additionally, calibration and design of the individual SISO controllersmay be costly and time consuming.

The ECM of the present disclosure generates the target values using amodel predictive control (MPC) module. The MPC module identifiespossible sets of target values based on an engine torque request. TheMPC module may determine predicted parameters for each of the possiblesets based on the possible sets' target values and a mathematical modelof the engine.

The MPC module may also determine a cost associated with use of each ofthe possible sets. The cost determined for a possible set increases asdifferences between the target values of the possible set and thereference value, respectively, increase and vice versa. In variousimplementations, instead of or in addition to identifying possible setsof target values and determining the cost of each of the sets, the MPCmodule may generate a surface representing the cost of possible sets oftarget values. The MPC module may then identify the possible set thathas the lowest cost based on the slope of the cost surface. The ECM ofthe present disclosure diagnoses faults in the MPC module. One or moreremedial actions may be taken when a fault is present in the MPC module.

Referring now to FIG. 1, a functional block diagram of an example enginesystem 100 is presented. The engine system 100 includes an engine 102that combusts an air/fuel mixture to produce drive torque for a vehiclebased on driver input from a driver input module 104. The engine 102 maybe a gasoline spark ignition internal combustion engine.

Air is drawn into an intake manifold 110 through a throttle valve 112.For example only, the throttle valve 112 may include a butterfly valvehaving a rotatable blade. An engine control module (ECM) 114 controls athrottle actuator module 116, which regulates opening of the throttlevalve 112 to control the amount of air drawn into the intake manifold110.

Air from the intake manifold 110 is drawn into cylinders of the engine102. While the engine 102 may include multiple cylinders, forillustration purposes a single representative cylinder 118 is shown. Forexample only, the engine 102 may include 2, 3, 4, 5, 6, 8, 10, and/or 12cylinders. The ECM 114 may instruct a cylinder actuator module 120 toselectively deactivate some of the cylinders, which may improve fueleconomy under certain engine operating conditions.

The engine 102 may operate using a four-stroke cycle. The four strokes,described below, may be referred to as the intake stroke, thecompression stroke, the combustion stroke, and the exhaust stroke.During each revolution of a crankshaft (not shown), two of the fourstrokes occur within the cylinder 118. Therefore, two crankshaftrevolutions are necessary for the cylinder 118 to experience all four ofthe strokes.

During the intake stroke, air from the intake manifold 110 is drawn intothe cylinder 118 through an intake valve 122. The ECM 114 controls afuel actuator module 124, which regulates fuel injection to achieve atarget air/fuel ratio. Fuel may be injected into the intake manifold 110at a central location or at multiple locations, such as near the intakevalve 122 of each of the cylinders. In various implementations (notshown), fuel may be injected directly into the cylinders or into mixingchambers associated with the cylinders. The fuel actuator module 124 mayhalt injection of fuel to cylinders that are deactivated.

The injected fuel mixes with air and creates an air/fuel mixture in thecylinder 118. During the compression stroke, a piston (not shown) withinthe cylinder 118 compresses the air/fuel mixture. A spark actuatormodule 126 energizes a spark plug 128 in the cylinder 118 based on asignal from the ECM 114, which ignites the air/fuel mixture. The timingof the spark may be specified relative to the time when the piston is atits topmost position, referred to as top dead center (TDC).

The spark actuator module 126 may be controlled by a timing signalspecifying how far before or after TDC to generate the spark. Becausepiston position is directly related to crankshaft rotation, operation ofthe spark actuator module 126 may be synchronized with crankshaft angle.Generating spark may be referred to as a firing event. The sparkactuator module 126 may have the ability to vary the timing of the sparkfor each firing event. The spark actuator module 126 may vary the sparktiming for a next firing event when the spark timing is changed betweena last firing event and the next firing event. The spark actuator module126 may halt provision of spark to deactivated cylinders.

During the combustion stroke, the combustion of the air/fuel mixturedrives the piston away from TDC, thereby driving the crankshaft. Thecombustion stroke may be defined as the time between the piston reachingTDC and the time at which the piston reaches bottom dead center (BDC).During the exhaust stroke, the piston begins moving away from BDC andexpels the byproducts of combustion through an exhaust valve 130. Thebyproducts of combustion are exhausted from the vehicle via an exhaustsystem 134.

The intake valve 122 may be controlled by an intake camshaft 140, whilethe exhaust valve 130 may be controlled by an exhaust camshaft 142. Invarious implementations, multiple intake camshafts (including the intakecamshaft 140) may control multiple intake valves (including the intakevalve 122) for the cylinder 118 and/or may control the intake valves(including the intake valve 122) of multiple banks of cylinders(including the cylinder 118). Similarly, multiple exhaust camshafts(including the exhaust camshaft 142) may control multiple exhaust valvesfor the cylinder 118 and/or may control exhaust valves (including theexhaust valve 130) for multiple banks of cylinders (including thecylinder 118). In various other implementations, the intake valve 122and/or the exhaust valve 130 may be controlled by devices other thancamshafts, such as camless valve actuators. The cylinder actuator module120 may deactivate the cylinder 118 by disabling opening of the intakevalve 122 and/or the exhaust valve 130.

The time when the intake valve 122 is opened may be varied with respectto piston TDC by an intake cam phaser 148. The time when the exhaustvalve 130 is opened may be varied with respect to piston TDC by anexhaust cam phaser 150. A phaser actuator module 158 may control theintake cam phaser 148 and the exhaust cam phaser 150 based on signalsfrom the ECM 114. When implemented, variable valve lift (not shown) mayalso be controlled by the phaser actuator module 158.

The engine system 100 may include a turbocharger that includes a hotturbine 160-1 that is powered by hot exhaust gases flowing through theexhaust system 134. The turbocharger also includes a cold air compressor160-2 that is driven by the turbine 160-1. The compressor 160-2compresses air leading into the throttle valve 112. In variousimplementations, a supercharger (not shown), driven by the crankshaft,may compress air from the throttle valve 112 and deliver the compressedair to the intake manifold 110.

A wastegate 162 may allow exhaust to bypass the turbine 160-1, therebyreducing the boost (the amount of intake air compression) provided bythe turbocharger. A boost actuator module 164 may control the boost ofthe turbocharger by controlling opening of the wastegate 162. In variousimplementations, two or more turbochargers may be implemented and may becontrolled by the boost actuator module 164.

An air cooler (not shown) may transfer heat from the compressed aircharge to a cooling medium, such as engine coolant or air. An air coolerthat cools the compressed air charge using engine coolant may bereferred to as an intercooler. An air cooler that cools the compressedair charge using air may be referred to as a charge air cooler. Thecompressed air charge may receive heat, for example, via compressionand/or from components of the exhaust system 134. Although shownseparated for purposes of illustration, the turbine 160-1 and thecompressor 160-2 may be attached to each other, placing intake air inclose proximity to hot exhaust.

The engine system 100 may include an exhaust gas recirculation (EGR)valve 170, which selectively redirects exhaust gas back to the intakemanifold 110. The EGR valve 170 may be located upstream of theturbocharger's turbine 160-1. The EGR valve 170 may be controlled by anEGR actuator module 172 based on signals from the ECM 114.

A position of the crankshaft may be measured using a crankshaft positionsensor 180. A rotational speed of the crankshaft (an engine speed) maybe determined based on the crankshaft position. A temperature of theengine coolant may be measured using an engine coolant temperature (ECT)sensor 182. The ECT sensor 182 may be located within the engine 102 orat other locations where the coolant is circulated, such as a radiator(not shown).

A pressure within the intake manifold 110 may be measured using amanifold absolute pressure (MAP) sensor 184. In various implementations,engine vacuum, which is the difference between ambient air pressure andthe pressure within the intake manifold 110, may be measured. A massflow rate of air flowing into the intake manifold 110 may be measuredusing a mass air flow (MAF) sensor 186. In various implementations, theMAF sensor 186 may be located in a housing that also includes thethrottle valve 112.

The throttle actuator module 116 may monitor the position of thethrottle valve 112 using one or more throttle position sensors (TPS)190. An ambient temperature of air being drawn into the engine 102 maybe measured using an intake air temperature (IAT) sensor 192. The enginesystem 100 may also include one or more other sensors 193, such as anambient humidity sensor, one or more knock sensors, a compressor outletpressure sensor and/or a throttle inlet pressure sensor, a wastegateposition sensor, an EGR position sensor, and/or one or more othersuitable sensors. The ECM 114 may use signals from the sensors to makecontrol decisions for the engine system 100.

The ECM 114 may communicate with a transmission control module 194 tocoordinate shifting gears in a transmission (not shown). For example,the ECM 114 may reduce engine torque during a gear shift. The ECM 114may communicate with a hybrid control module 196 to coordinate operationof the engine 102 and an electric motor 198.

The electric motor 198 may also function as a generator, and may be usedto produce electrical energy for use by vehicle electrical systemsand/or for storage in a battery. In various implementations, variousfunctions of the ECM 114, the transmission control module 194, and thehybrid control module 196 may be integrated into one or more modules.

Each system that varies an engine parameter may be referred to as anengine actuator. For example, the throttle actuator module 116 mayadjust opening of the throttle valve 112 to achieve a target throttleopening area. The spark actuator module 126 controls the spark plugs toachieve a target spark timing relative to piston TDC. The fuel actuatormodule 124 controls the fuel injectors to achieve target fuelingparameters. The phaser actuator module 158 may control the intake andexhaust cam phasers 148 and 150 to achieve target intake and exhaust camphaser angles, respectively. The EGR actuator module 172 may control theEGR valve 170 to achieve a target EGR opening area. The boost actuatormodule 164 controls the wastegate 162 to achieve a target wastegateopening area. The cylinder actuator module 120 controls cylinderdeactivation to achieve a target number of activated or deactivatedcylinders.

The ECM 114 generates the target values for the engine actuators tocause the engine 102 to generate a target engine output torque. The ECM114 generates the target values for the engine actuators using modelpredictive control, as discussed further below.

Referring now to FIG. 2, a functional block diagram of an example enginecontrol system is presented. An example implementation of the ECM 114includes a driver torque module 202, an axle torque arbitration module204, and a propulsion torque arbitration module 206. The ECM 114 mayinclude a hybrid optimization module 208. The ECM 114 also includes areserves/loads module 220, a torque requesting module 224, an aircontrol module 228, a spark control module 232, a cylinder controlmodule 236, and a fuel control module 240.

The driver torque module 202 may determine a driver torque request 254based on a driver input 255 from the driver input module 104. The driverinput 255 may be based on, for example, a position of an acceleratorpedal and a position of a brake pedal. The driver input 255 may also bebased on cruise control, which may be an adaptive cruise control systemthat varies vehicle speed to maintain a predetermined followingdistance. The driver torque module 202 may store one or more mappings ofaccelerator pedal position to target torque and may determine the drivertorque request 254 based on a selected one of the mappings.

An axle torque arbitration module 204 arbitrates between the drivertorque request 254 and other axle torque requests 256. Axle torque(torque at the wheels) may be produced by various sources including anengine and/or an electric motor. For example, the axle torque requests256 may include a torque reduction requested by a traction controlsystem when positive wheel slip is detected. Positive wheel slip occurswhen axle torque overcomes friction between the wheels and the roadsurface, and the wheels begin to slip against the road surface. The axletorque requests 256 may also include a torque increase request tocounteract negative wheel slip, where a tire of the vehicle slips in theother direction with respect to the road surface because the axle torqueis negative.

The axle torque requests 256 may also include brake management requestsand vehicle over-speed torque requests. Brake management requests mayreduce axle torque to ensure that the axle torque does not exceed theability of the brakes to hold the vehicle when the vehicle is stopped.Vehicle over-speed torque requests may reduce the axle torque to preventthe vehicle from exceeding a predetermined speed. The axle torquerequests 256 may also be generated by vehicle stability control systems.

The axle torque arbitration module 204 outputs a predicted torquerequest 257 and an immediate torque request 258 based on the results ofarbitrating between the received torque requests 254 and 256. Asdescribed below, the predicted and immediate torque requests 257 and 258from the axle torque arbitration module 204 may selectively be adjustedby other modules of the ECM 114 before being used to control the engineactuators.

In general terms, the immediate torque request 258 may be an amount ofcurrently desired axle torque, while the predicted torque request 257may be an amount of axle torque that may be needed on short notice. TheECM 114 controls the engine system 100 to produce an axle torque equalto the immediate torque request 258. However, different combinations oftarget values may result in the same axle torque. The ECM 114 maytherefore adjust the target values to enable a faster transition to thepredicted torque request 257, while still maintaining the axle torque atthe immediate torque request 258.

In various implementations, the predicted torque request 257 may be setbased on the driver torque request 254. The immediate torque request 258may be set to less than the predicted torque request 257 under somecircumstances, such as when the driver torque request 254 is causingwheel slip on an icy surface. In such a case, a traction control system(not shown) may request a reduction via the immediate torque request258, and the ECM 114 reduces the engine torque output to the immediatetorque request 258. However, the ECM 114 performs the reduction so theengine system 100 can quickly resume producing the predicted torquerequest 257 once the wheel slip stops.

In general terms, the difference between the immediate torque request258 and the (generally higher) predicted torque request 257 can bereferred to as a torque reserve. The torque reserve may represent theamount of additional torque (above the immediate torque request 258)that the engine system 100 can begin to produce with minimal delay. Fastengine actuators are used to increase or decrease current axle torquewith minimal delay. Fast engine actuators are defined in contrast withslow engine actuators.

In general terms, fast engine actuators can change the axle torque morequickly than slow engine actuators. Slow actuators may respond moreslowly to changes in their respective target values than fast actuatorsdo. For example, a slow actuator may include mechanical components thatrequire time to move from one position to another in response to achange in target value. A slow actuator may also be characterized by theamount of time it takes for the axle torque to begin to change once theslow actuator begins to implement the changed target value. Generally,this amount of time will be longer for slow actuators than for fastactuators. In addition, even after beginning to change, the axle torquemay take longer to fully respond to a change in a slow actuator.

For example only, the spark actuator module 126 may be a fast actuator.Spark-ignition engines may combust fuels including, for example,gasoline and ethanol, by applying a spark. By way of contrast, thethrottle actuator module 116 may be a slow actuator.

For example, as described above, the spark actuator module 126 can varythe spark timing for a next firing event when the spark timing ischanged between a last firing event and the next firing event. By way ofcontrast, changes in throttle opening take longer to affect engineoutput torque. The throttle actuator module 116 changes the throttleopening by adjusting the angle of the blade of the throttle valve 112.Therefore, when the target value for opening of the throttle valve 112is changed, there is a mechanical delay as the throttle valve 112 movesfrom its previous position to a new position in response to the change.In addition, air flow changes based on the throttle opening are subjectto air transport delays in the intake manifold 110. Further, increasedair flow in the intake manifold 110 is not realized as an increase inengine output torque until the cylinder 118 receives additional air inthe next intake stroke, compresses the additional air, and commences thecombustion stroke.

Using these actuators as an example, a torque reserve can be created bysetting the throttle opening to a value that would allow the engine 102to produce the predicted torque request 257. Meanwhile, the spark timingcan be set based on the immediate torque request 258, which is less thanthe predicted torque request 257. Although the throttle openinggenerates enough air flow for the engine 102 to produce the predictedtorque request 257, the spark timing is retarded (which reduces torque)based on the immediate torque request 258. The engine output torque willtherefore be equal to the immediate torque request 258.

When additional torque is needed, the spark timing can be set based onthe predicted torque request 257 or a torque between the predicted andimmediate torque requests 257 and 258. By the following firing event,the spark actuator module 126 may return the spark timing to an optimumvalue, which allows the engine 102 to produce the full engine outputtorque achievable with the air flow already present. The engine outputtorque may therefore be quickly increased to the predicted torquerequest 257 without experiencing delays from changing the throttleopening.

The axle torque arbitration module 204 may output the predicted torquerequest 257 and the immediate torque request 258 to a propulsion torquearbitration module 206. In various implementations, the axle torquearbitration module 204 may output the predicted and immediate torquerequests 257 and 258 to the hybrid optimization module 208.

The hybrid optimization module 208 may determine how much torque shouldbe produced by the engine 102 and how much torque should be produced bythe electric motor 198. The hybrid optimization module 208 then outputsmodified predicted and immediate torque requests 259 and 260,respectively, to the propulsion torque arbitration module 206. Invarious implementations, the hybrid optimization module 208 may beimplemented in the hybrid control module 196.

The predicted and immediate torque requests received by the propulsiontorque arbitration module 206 are converted from an axle torque domain(torque at the wheels) into a propulsion torque domain (torque at thecrankshaft). This conversion may occur before, after, as part of, or inplace of the hybrid optimization module 208.

The propulsion torque arbitration module 206 arbitrates betweenpropulsion torque requests 290, including the converted predicted andimmediate torque requests. The propulsion torque arbitration module 206generates an arbitrated predicted torque request 261 and an arbitratedimmediate torque request 262. The arbitrated torque requests 261 and 262may be generated by selecting a winning request from among receivedtorque requests. Alternatively or additionally, the arbitrated torquerequests may be generated by modifying one of the received requestsbased on another one or more of the received torque requests.

For example, the propulsion torque requests 290 may include torquereductions for engine over-speed protection, torque increases for stallprevention, and torque reductions requested by the transmission controlmodule 194 to accommodate gear shifts. The propulsion torque requests290 may also result from clutch fuel cutoff, which reduces the engineoutput torque when the driver depresses the clutch pedal in a manualtransmission vehicle to prevent a flare in engine speed.

The propulsion torque requests 290 may also include an engine shutoffrequest, which may be initiated when a critical fault is detected. Forexample only, critical faults may include detection of vehicle theft, astuck starter motor, electronic throttle control problems, andunexpected torque increases. In various implementations, when an engineshutoff request is present, arbitration selects the engine shutoffrequest as the winning request. When the engine shutoff request ispresent, the propulsion torque arbitration module 206 may output zero asthe arbitrated predicted and immediate torque requests 261 and 262.

In various implementations, an engine shutoff request may simply shutdown the engine 102 separately from the arbitration process. Thepropulsion torque arbitration module 206 may still receive the engineshutoff request so that, for example, appropriate data can be fed backto other torque requestors. For example, all other torque requestors maybe informed that they have lost arbitration.

The reserves/loads module 220 receives the arbitrated predicted andimmediate torque requests 261 and 262. The reserves/loads module 220 mayadjust the arbitrated predicted and immediate torque requests 261 and262 to create a torque reserve and/or to compensate for one or moreloads. The reserves/loads module 220 then outputs adjusted predicted andimmediate torque requests 263 and 264 to the torque requesting module224.

For example only, a catalyst light-off process or a cold start emissionsreduction process may require retarded spark timing. The reserves/loadsmodule 220 may therefore increase the adjusted predicted torque request263 above the adjusted immediate torque request 264 to create retardedspark for the cold start emissions reduction process. In anotherexample, the air/fuel ratio of the engine and/or the mass air flow maybe directly varied, such as by diagnostic intrusive equivalence ratiotesting and/or new engine purging. Before beginning these processes, atorque reserve may be created or increased to quickly offset decreasesin engine output torque that result from leaning the air/fuel mixtureduring these processes.

The reserves/loads module 220 may also create or increase a torquereserve in anticipation of a future load, such as power steering pumpoperation or engagement of an air conditioning (NC) compressor clutch.The reserve for engagement of the NC compressor clutch may be createdwhen the driver first requests air conditioning. The reserves/loadsmodule 220 may increase the adjusted predicted torque request 263 whileleaving the adjusted immediate torque request 264 unchanged to producethe torque reserve. Then, when the NC compressor clutch engages, thereserves/loads module 220 may increase the adjusted immediate torquerequest 264 by the estimated load of the NC compressor clutch.

The torque requesting module 224 receives the adjusted predicted andimmediate torque requests 263 and 264. The torque requesting module 224determines how the adjusted predicted and immediate torque requests 263and 264 will be achieved. The torque requesting module 224 may be enginetype specific. For example, the torque requesting module 224 may beimplemented differently or use different control schemes forspark-ignition engines versus compression-ignition engines.

In various implementations, the torque requesting module 224 may definea boundary between modules that are common across all engine types andmodules that are engine type specific. For example, engine types mayinclude spark-ignition and compression-ignition. Modules prior to thetorque requesting module 224, such as the propulsion torque arbitrationmodule 206, may be common across engine types, while the torquerequesting module 224 and subsequent modules may be engine typespecific.

The torque requesting module 224 determines an air torque request 265based on the adjusted predicted and immediate torque requests 263 and264. The air torque request 265 may be a brake torque. Brake torque mayrefer to torque at the crankshaft under the current operatingconditions.

Target values for airflow controlling engine actuators are determinedbased on the air torque request 265. More specifically, based on the airtorque request 265, the air control module 228 determines a targetwastegate opening area 266, a target throttle opening area 267, a targetEGR opening area 268, a target intake cam phaser angle 269, and a targetexhaust cam phaser angle 270. The air control module 228 determines thetarget wastegate opening area 266, the target throttle opening area 267,the target EGR opening area 268, the target intake cam phaser angle 269,and the target exhaust cam phaser angle 270 using model predictivecontrol, as discussed further below.

The boost actuator module 164 controls the wastegate 162 to achieve thetarget wastegate opening area 266. For example, a first conversionmodule 272 may convert the target wastegate opening area 266 into atarget duty cycle 274 to be applied to the wastegate 162, and the boostactuator module 164 may apply a signal to the wastegate 162 based on thetarget duty cycle 274. In various implementations, the first conversionmodule 272 may convert the target wastegate opening area 266 into atarget wastegate position (not shown), and convert the target wastegateposition into the target duty cycle 274.

The throttle actuator module 116 controls the throttle valve 112 toachieve the target throttle opening area 267. For example, a secondconversion module 276 may convert the target throttle opening area 267into a target duty cycle 278 to be applied to the throttle valve 112,and the throttle actuator module 116 may apply a signal to the throttlevalve 112 based on the target duty cycle 278. In variousimplementations, the second conversion module 276 may convert the targetthrottle opening area 267 into a target throttle position (not shown),and convert the target throttle position into the target duty cycle 278.

The EGR actuator module 172 controls the EGR valve 170 to achieve thetarget EGR opening area 268. For example, a third conversion module 280may convert the target EGR opening area 268 into a target duty cycle 282to be applied to the EGR valve 170, and the EGR actuator module 172 mayapply a signal to the EGR valve 170 based on the target duty cycle 282.In various implementations, the third conversion module 280 may convertthe target EGR opening area 268 into a target EGR position (not shown),and convert the target EGR position into the target duty cycle 282.

The phaser actuator module 158 controls the intake cam phaser 148 toachieve the target intake cam phaser angle 269. The phaser actuatormodule 158 also controls the exhaust cam phaser 150 to achieve thetarget exhaust cam phaser angle 270. In various implementations, afourth conversion module (not shown) may be included and may convert thetarget intake and exhaust cam phaser angles into target intake andexhaust duty cycles, respectively. The phaser actuator module 158 mayapply the target intake and exhaust duty cycles to the intake andexhaust cam phasers 148 and 150, respectively. In variousimplementations, the air control module 228 may determine a targetoverlap factor and a target effective displacement, and the phaseractuator module 158 may control the intake and exhaust cam phasers 148and 150 to achieve the target overlap factor and the target effectivedisplacement.

The torque requesting module 224 may also generate a spark torquerequest 283, a cylinder shut-off torque request 284, and a fuel torquerequest 285 based on the predicted and immediate torque requests 263 and264. The spark control module 232 may determine how much to retard thespark timing (which reduces engine output torque) from an optimum sparktiming based on the spark torque request 283. For example only, a torquerelationship may be inverted to solve for a target spark timing 286. Fora given torque request (T_(Req)), the target spark timing (S_(T)) 286may be determined based on:S _(T) =f ¹(T _(Req),APC,I,E,AF,OT,#),  (1)where APC is an APC, I is an intake valve phasing value, E is an exhaustvalve phasing value, AF is an air/fuel ratio, OT is an oil temperature,and # is a number of activated cylinders. This relationship may beembodied as an equation and/or as a lookup table. The air/fuel ratio(AF) may be the actual air/fuel ratio, as reported by the fuel controlmodule 240.

When the spark timing is set to the optimum spark timing, the resultingtorque may be as close to a minimum spark advance for best torque (MBTspark timing) as possible. Best torque refers to the maximum engineoutput torque that is generated for a given air flow as spark timing isadvanced, while using fuel having an octane rating greater than apredetermined octane rating and using stoichiometric fueling. The sparktiming at which this best occurs is referred to as an MBT spark timing.The optimum spark timing may differ slightly from MBT spark timingbecause of, for example, fuel quality (such as when lower octane fuel isused) and environmental factors, such as ambient humidity andtemperature. The engine output torque at the optimum spark timing maytherefore be less than MBT. For example only, a table of optimum sparktimings corresponding to different engine operating conditions may bedetermined during a calibration phase of vehicle design, and the optimumvalue is determined from the table based on current engine operatingconditions.

The cylinder shut-off torque request 284 may be used by the cylindercontrol module 236 to determine a target number of cylinders todeactivate 287. In various implementations, a target number of cylindersto activate may be used. The cylinder actuator module 120 selectivelyactivates and deactivates the valves of cylinders based on the targetnumber 287.

The cylinder control module 236 may also instruct the fuel controlmodule 240 to stop providing fuel for deactivated cylinders and mayinstruct the spark control module 232 to stop providing spark fordeactivated cylinders. The spark control module 232 may stop providingspark to a cylinder once an fuel/air mixture that is already present inthe cylinder has been combusted.

The fuel control module 240 may vary the amount of fuel provided to eachcylinder based on the fuel torque request 285. More specifically, thefuel control module 240 may generate target fueling parameters 288 basedon the fuel torque request 285. The target fueling parameters 288 mayinclude, for example, target mass of fuel, target injection startingtiming, and target number of fuel injections.

During normal operation, the fuel control module 240 may operate in anair lead mode in which the fuel control module 240 attempts to maintaina stoichiometric air/fuel ratio by controlling fueling based on airflow. For example, the fuel control module 240 may determine a targetfuel mass that will yield stoichiometric combustion when combined with apresent mass of air per cylinder (APC).

FIG. 3 is a functional block diagram of an example implementation of theair control module 228. Referring now to FIGS. 2 and 3, as discussedabove, the air torque request 265 may be a brake torque. A torqueconversion module 304 converts the air torque request 265 from braketorque into base torque. The torque request resulting from conversioninto base torque will be referred to as a base air torque request 308.

Base torques may refer to torque at the crankshaft made during operationof the engine 102 on a dynamometer while the engine 102 is warm and notorque loads are imposed on the engine 102 by accessories, such as analternator and the NC compressor. The torque conversion module 304 mayconvert the air torque request 265 into the base air torque request 308,for example, using a mapping or a function that relates brake torques tobase torques. In various implementations, the torque conversion module304 may convert the air torque request 265 into another suitable type oftorque, such as an indicated torque. An indicated torque may refer to atorque at the crankshaft attributable to work produced via combustionwithin the cylinders.

An MPC module 312 generates the target values 266-270 using MPC (ModelPredictive Control). The MPC module 312 may be a single module or maycomprise multiple modules. For example, the MPC module 312 may include asequence determination module 316. The sequence determination module 316determines possible sequences of the target values 266-270 that could beused together during N future control loops. Each of the possiblesequences identified by the sequence determination module 316 includesone sequence of N values for each of the target values 266-270. In otherwords, each possible sequence includes a sequence of N values for thetarget wastegate opening area 266, a sequence of N values for the targetthrottle opening area 267, a sequence of N values for the target EGRopening area 268, a sequence of N values for the target intake camphaser angle 269, and a sequence of N values for the target exhaust camphaser angle 270. Each of the N values are for a corresponding one ofthe N future control loops. N is an integer greater than or equal toone.

A prediction module 323 determines predicted responses of the engine 102to the possible sequences of the target values 266-270, respectively,based on a mathematical model 324 of the engine 102, exogenous inputs328, and feedback inputs 330. More specifically, based on a possiblesequence of the target values 266-270, the exogenous inputs 328, and thefeedback inputs 330, using the model 324, the prediction module 323generates a sequence of predicted torques of the engine 102 for the Ncontrol loops, a sequence of predicted APCs for the N control loops, asequence of predicted amounts of external dilution for the N controlloops, a sequence of predicted amounts of residual dilution for the Ncontrol loops, a sequence of predicted combustion phasing values for theN control loops, and a sequence of predicted combustion quality valuesfor the N control loops. While an example of generating predictedtorque, predicted APC, predicted external dilution, predicted residualdilution, predicted combustion phasing, and predicted combustion qualityis described, the predicted parameters may include one or more otherpredicted engine operating parameters.

The model 324 may include, for example, a function or a mappingcalibrated based on characteristics of the engine 102. Dilution mayrefer to an amount of exhaust from a prior combustion event trappedwithin a cylinder for a combustion event. External dilution may refer toexhaust provided for a combustion event via the EGR valve 170. Residualdilution may refer to exhaust that remains in a cylinder and/or exhaustthat is pushed back into the cylinder following the exhaust stroke of acombustion cycle. Residual dilution may also be referred to as internaldilution.

Combustion phasing may refer to a crankshaft position where apredetermined amount of fuel injected is combusted within a cylinderrelative to a predetermined crankshaft position for combustion of thepredetermined amount of injected fuel. For example, combustion phasingmay be expressed in terms of CA50 relative to a predetermined CA50. CA50may refer to a crankshaft angle (CA) where 50 percent of a mass ofinjected fuel has been combusted within a cylinder. The predeterminedCA50 may correspond to a CA50 where a maximum amount of work is producedfrom the fuel injected and may be approximately 8.5-approximately 10degrees after TDC (top dead center) in various implementations. Whilecombustion phasing will be discussed in terms of CA50 values, anothersuitable parameter indicative of combustion phasing may be used.Additionally, while combustion quality will be discussed as coefficientof variation (COV) of indicated mean effective pressure (IMEP) values,another suitable parameter indicative of combustion quality may be used.

The exogenous inputs 328 may include parameters that are not directlyaffected by the throttle valve 112, the EGR valve 170, the turbocharger,the intake cam phaser 148, and the exhaust cam phaser 150. For example,the exogenous inputs 328 may include engine speed, turbocharger inletair pressure, IAT, and/or one or more other parameters. The feedbackinputs 330 may include, for example, an estimated torque output of theengine 102, an exhaust pressure downstream of the turbine 160-1 of theturbocharger, the IAT, an APC of the engine 102, an estimated residualdilution, an estimated external dilution, and/or one or more othersuitable parameters. The feedback inputs 330 may be measured usingsensors (e.g., the IAT) and/or estimated based on one or more otherparameters.

For example, the prediction module 323 may generate the predictedparameters for a given sequence of possible target values based on therelationships:x(k+1)=Ax(k)+Bu(k); andy(k)=Cx(k),where k is a current control loop, x(k+1) is a vector with entriesindicative of states of the engine 102 for a next control loop k+1, A isa matrix including constant values calibrated based on characteristicsof the engine 102, x(k) is a vector with entries indicative of states ofthe engine 102 for the current control loop, B is a matrix includingconstant values calibrated based on characteristics of the engine 102,u(k) is a vector of including entries for the possible target values forthe current control loop, y(k) is a vector including the predictedparameters for the current control loop, and C is a matrix includingconstant values calibrated based on characteristics of the engine 102.The vector x(k+1) determined during the current control loop will beused as the vector x(k) during the next control loop. The relationshipscould therefore also be written as:x(k)=Ax(k−1)+Bu(k−1); andy(k)=Cx(k),where k is a current control loop, x(k−1) is a vector with entriesindicative of states of the engine 102 for a last control loop, A is amatrix including constant values calibrated based on characteristics ofthe engine 102, x(k) is a vector with entries indicative of states ofthe engine 102 for the current control loop, B is a matrix includingconstant values calibrated based on characteristics of the engine 102,u(k−1) is a vector of including entries for the possible target valuesfor the last control loop.

How the components of the above relationships can be re-written for theexample of the predicted parameters including predicted torque predictedAPC, predicted external dilution, predicted residual dilution, predictedcombustion phasing, and predicted combustion quality will now bedescribed. The vector x(k+1) can be re-written as:

${{x\left( {k + 1} \right)} = \begin{bmatrix}{x\; 1\left( {k + 1} \right)} \\{x\; 2\left( {k + 1} \right)} \\{x\; 3\left( {k + 1} \right)} \\{x\; 4\left( {k + 1} \right)} \\{x\; 5\left( {k + 1} \right)} \\{x\; 6\left( {k + 1} \right)}\end{bmatrix}},$where x1(k+1) is a first state parameter of the engine 102 for the nextcontrol loop, x2(k+1) is a second state parameter of the engine 102 forthe next control loop, x3(k+1) is a third state parameter of the engine102 for the next control loop, x4(k+1) is a fourth state parameter ofthe engine 102 for the next control loop, x5(k+1) is a fifth stateparameter of the engine 102 for the next control loop, and x6(k+1) is asixth state parameter of the engine 102 for the next control loop.

The matrix A can be re-written as:

$A = \begin{bmatrix}{a\; 11} & {a\; 12} & {a\; 13} & {a\; 14} & {a\; 15} & {a\; 16} \\{a\; 21} & {a\; 22} & {a\; 23} & {a\; 24} & {a\; 25} & {a\; 26} \\{a\; 31} & {a\; 32} & {a\; 33} & {a\; 34} & {a\; 35} & {a\; 36} \\{a\; 41} & {a\; 42} & {a\; 43} & {a\; 44} & {a\; 45} & {a\; 46} \\{a\; 51} & {a\; 52} & {a\; 53} & {a\; 54} & {a\; 55} & {a\; 56} \\{a\; 61} & {a\; 62} & {a\; 63} & {a\; 64} & {a\; 65} & {a\; 66}\end{bmatrix}$where a11-a66 are constant values calibrated based on characteristics ofthe engine 102.

The vector x(k) can be re-written as:

${{x(k)} = \begin{bmatrix}{x\; 1(k)} \\{x\; 2(k)} \\{x\; 3(k)} \\{x\; 4(k)} \\{x\; 5(k)} \\{x\; 6(k)}\end{bmatrix}},$where x1(k) is the first state parameter of the engine 102 for thecurrent control loop, x2(k) is the second state parameter of the engine102 for the current control loop, x3(k) is the third state parameter ofthe engine 102 for current control loop, x4(k) is the fourth stateparameter of the engine 102 for the current control loop, x5(k) is thefifth state parameter of the engine 102 for the current control loop,and x6(k) is the sixth state parameter of the engine 102 for the currentcontrol loop. The entries of the vector x(k) are the entries of thevector x(k+1) calculated during the previous control loop. The entriesof the vector x(k+1) calculated during the current control loop are usedduring the next control loop as the entries of vector x(k).

The matrix B can be re-written as:

$B = \begin{bmatrix}{b\; 11} & {b\; 12} & {b\; 13} & {b\; 14} & {b\; 15} \\{b\; 21} & {b\; 22} & {b\; 23} & {b\; 24} & {b\; 25} \\{b\; 31} & {b\; 32} & {b\; 33} & {b\; 34} & {b\; 35} \\{b\; 41} & {b\; 42} & {b\; 43} & {b\; 44} & {b\; 45} \\{b\; 51} & {b\; 52} & {b\; 53} & {b\; 54} & {b\; 55} \\{b\; 61} & {b\; 62} & {b\; 63} & {b\; 64} & {b\; 65}\end{bmatrix}$where b11-b65 are constant values calibrated based on characteristics ofthe engine 102.

The vector u(k) can be re-written as:

${{u(k)} = \begin{bmatrix}{PTT} \\{PTWG} \\{PTEGR} \\{PTICP} \\{PTECP}\end{bmatrix}},$where PTT is a possible target throttle opening of a possible sequencefor the current control loop, PTWG is a possible target wastegateopening of the possible sequence for the current control loop, PTEGR isa possible target EGR opening of the possible sequence for the currentcontrol loop, PTICP is a possible target intake cam phasing value of thepossible sequence for the current control loop, and PTECP is a possibletarget exhaust cam phasing value of the possible sequence for thecurrent control loop.

The vector y(k) can be re-written as:

${{y(k)} = \begin{bmatrix}{PT} \\{PAPC} \\{PED} \\{PRD} \\{PCP} \\{PCQ}\end{bmatrix}},$where PT is a predicted torque of the engine 102 for the current controlloop, PAPC is a predicted APC of the engine 102 for the current controlloop, PED is a predicted amount of external dilution for the currentcontrol loop, PRD is a predicted amount of residual dilution for thecurrent control loop, PCP is a predicted combustion phasing for thecurrent control loop, and PCQ is a predicted combustion quality for thecurrent control loop.

The matrix C can be re-written as:

$C = \begin{bmatrix}{c\; 11} & {c\; 12} & {c\; 13} & {c\; 14} & {c\; 15} & {c\; 16} \\{c\; 21} & {c\; 22} & {c\; 23} & {c\; 24} & {c\; 25} & {c\; 26} \\{c\; 31} & {c\; 32} & {c\; 33} & {c\; 34} & {c\; 35} & {c\; 36} \\{c\; 41} & {c\; 42} & {c\; 43} & {c\; 44} & {c\; 45} & {c\; 46} \\{c\; 51} & {c\; 52} & {c\; 53} & {c\; 54} & {c\; 55} & {c\; 56} \\{c\; 61} & {c\; 62} & {c\; 63} & {c\; 64} & {c\; 65} & {c\; 66}\end{bmatrix}$where c11-c66 are constant values calibrated based on characteristics ofthe engine 102.

The model 324 includes several different sets of the A, B, and Cmatrices for different operating conditions. The prediction module 323selects which set of the A, B, and C matrices to use based on the enginespeed, engine load, and/or one or more other parameters.

For the example of the predicted parameters including predicted torquepredicted APC, predicted external dilution, predicted residual dilution,predicted combustion phasing, and predicted combustion quality, theabove relationships can therefore be re-written as:

$\begin{bmatrix}{x\; 1\left( {k + 1} \right)} \\{x\; 2\left( {k + 1} \right)} \\{x\; 3\left( {k + 1} \right)} \\{x\; 4\left( {k + 1} \right)} \\{x\; 5\left( {k + 1} \right)} \\{x\; 6\left( {k + 1} \right)}\end{bmatrix} = {\begin{bmatrix}{a\; 11} & {a\; 12} & {a\; 13} & {a\; 14} & {a\; 15} & {a\; 16} \\{a\; 21} & {a\; 22} & {a\; 23} & {a\; 24} & {a\; 25} & {a\; 26} \\{a\; 31} & {a\; 32} & {a\; 33} & {a\; 34} & {a\; 35} & {a\; 36} \\{a\; 41} & {a\; 42} & {a\; 43} & {a\; 44} & {a\; 45} & {a\; 46} \\{a\; 51} & {a\; 52} & {a\; 53} & {a\; 54} & {a\; 55} & {a\; 56} \\{a\; 61} & {a\; 62} & {a\; 63} & {a\; 64} & {a\; 65} & {a\; 66}\end{bmatrix}{\quad{{\begin{bmatrix}{x\; 1(k)} \\{x\; 2(k)} \\{x\; 3(k)} \\{x\; 4(k)} \\{x\; 5(k)} \\{x\; 6(k)}\end{bmatrix} + {\begin{bmatrix}{b\; 11} & {b\; 12} & {b\; 13} & {b\; 14} & {b\; 15} \\{b\; 21} & {b\; 22} & {b\; 23} & {b\; 24} & {b\; 25} \\{b\; 31} & {b\; 32} & {b\; 33} & {b\; 34} & {b\; 35} \\{b\; 41} & {b\; 42} & {b\; 43} & {b\; 44} & {b\; 45} \\{b\; 51} & {b\; 52} & {b\; 53} & {b\; 54} & {b\; 55} \\{b\; 61} & {b\; 62} & {b\; 63} & {b\; 64} & {b\; 65}\end{bmatrix}\begin{bmatrix}{PTT} \\{PTWG} \\{PTEGR} \\{PTICP} \\{PTECP}\end{bmatrix}}};\mspace{20mu}{{{and}\mspace{20mu}\begin{bmatrix}{PT} \\{PAPC} \\{PED} \\{PRD} \\{PCP} \\{PCQ}\end{bmatrix}} = {{\begin{bmatrix}{c\; 11} & {c\; 12} & {c\; 13} & {c\; 14} & {c\; 15} & {c\; 16} \\{c\; 21} & {c\; 22} & {c\; 23} & {c\; 24} & {c\; 25} & {c\; 26} \\{c\; 31} & {c\; 32} & {c\; 33} & {c\; 34} & {c\; 35} & {c\; 36} \\{c\; 41} & {c\; 42} & {c\; 43} & {c\; 44} & {c\; 45} & {c\; 46} \\{c\; 51} & {c\; 52} & {c\; 53} & {c\; 54} & {c\; 55} & {c\; 56} \\{c\; 61} & {c\; 62} & {c\; 63} & {c\; 64} & {c\; 65} & {c\; 66}\end{bmatrix}\begin{bmatrix}{x\; 1(k)} \\{x\; 2(k)} \\{x\; 3(k)} \\{x\; 4(k)} \\{x\; 5(k)} \\{x\; 6(k)}\end{bmatrix}}.}}}}}$

The prediction module 323 may also adjust one or more of the predictedparameters based on differences between the predicted parameters andmeasured or estimated values of those parameters, respectively. Forexample, the prediction module 323 may include one or more integrators,such as one integrator for each of the predicted parameters. Anintegrator may determine an integrator value based on differencesbetween a predicted parameter and a measured or estimated value of thatparameter over a period of time.

For example, an integrator may determine a torque integrator value basedon differences between the predicted torque and measured or estimatedvalues of engine torque. Another integrator may determine an APCintegrator value based on differences between the predicted APC andmeasured or estimated values of APC. The prediction module 323 mayadjust the predicted parameters based on the associated integratorvalues before the predicted parameters are used in the costdetermination. For example, the prediction module 323 may adjust thepredicted torque based on the torque integrator value, adjust thepredicted APC based on the APC integrator value, etc.

A cost module 332 determines a cost value for each of the possiblesequences of the target values 266-270 based on the predicted parametersdetermined for a possible sequence and output reference values 356. Anexample cost determination is discussed further below.

A selection module 344 selects one of the possible sequences of thetarget values 266-270 based on the costs of the possible sequences,respectively. For example, the selection module 344 may select the oneof the possible sequences having the lowest cost while satisfyingactuator constraints 348 and output constraints 352. In variousimplementations, the model 324 may select the one of the possiblesequences having the lowest cost while satisfying the actuatorconstraints 348 and the output constraints 352.

In various implementations, satisfaction of the actuator constraints 348and the output constraints may be considered in the cost determination.In other words, the cost module 332 may determine the cost valuesfurther based on the actuator constraints 348 and the output constraints352. As discussed further below, based on how the cost values aredetermined, the selection module 344 will select the one of the possiblesequences that best achieves the base air torque request 308 whileminimizing the APC, subject to the actuator constraints 348 and theoutput constraints 352.

The selection module 344 may set the target values 266-270 to the firstones of the N values of the selected possible sequence, respectively. Inother words, the selection module 344 may set the target wastegateopening area 266 to the first one of the N values in the sequence of Nvalues for the target wastegate opening area 266, set the targetthrottle opening area 267 to the first one of the N values in thesequence of N values for the target throttle opening area 267, set thetarget EGR opening area 268 to the first one of the N values in thesequence of N values for the target EGR opening area 268, set the targetintake cam phaser angle 269 to the first one of the N values in thesequence of N values for the target intake cam phaser angle 269, and setthe target exhaust cam phaser angle 270 to the first one of the N valuesin the sequence of N values for the target exhaust cam phaser angle 270.

During a next control loop, the MPC module 312 identifies possiblesequences, generates the predicted parameters for the possiblesequences, determines the cost of each of the possible sequences,selects of one of the possible sequences, and sets of the target values266-270 to the first set of the target values 266-270 in the selectedpossible sequence. This process continues for each control loop.

An actuator constraint module 360 (see FIG. 2) sets the actuatorconstraints 348 for each of the target values 266-270. In other words,the actuator constraint module 360 sets actuator constraints for thethrottle valve 112, actuator constraints for the EGR valve 170, actuatorconstraints for the wastegate 162, actuator constraints for the intakecam phaser 148, and actuator constraints for the exhaust cam phaser 150.

The actuator constraints 348 for each one of the target values 266-270may include a maximum value for an associated target value and a minimumvalue for that target value. The actuator constraint module 360 maygenerally set the actuator constraints 348 to predetermined operationalranges for the associated actuators. More specifically, the actuatorconstraint module 360 may generally set the actuator constraints 348 topredetermined operational ranges for the throttle valve 112, the EGRvalve 170, the wastegate 162, the intake cam phaser 148, and the exhaustcam phaser 150, respectively.

However, the actuator constraint module 360 may selectively adjust oneor more of the actuator constraints 348 under some circumstances. Forexample, the actuator constraint module 360 may adjust the actuatorconstraints for a given actuator to narrow the operational range forthat engine actuator when a fault is diagnosed in that engine actuator.For another example only, the actuator constraint module 360 may adjustthe actuator constraints such that the target value for a given actuatorfollows a predetermined schedule over time or changes by a predeterminedamount, for example, for a fault diagnostic, such as a cam phaser faultdiagnostic, a throttle diagnostic, an EGR diagnostic, etc. For a targetvalue to follow a predetermined schedule over time or to change by apredetermined amount, the actuator constraint module 360 may set theminimum and maximum values to the same value. The minimum and maximumvalues being set to the same value may force the corresponding targetvalue to be set to the same value as the minimum and maximum values. Theactuator constraint module 360 may vary the same value to which theminimum and maximum values are set over time to cause the target valueto follow a predetermined schedule.

An output constraint module 364 (see FIG. 2) sets the output constraints352 for the predicted torque output of the engine 102, the predictedCA50, the predicted COV of IMEP, the predicted residual dilution, andthe predicted external dilution. The output constraints 352 for each oneof the predicted values may include a maximum value for an associatedpredicted parameter and a minimum value for that predicted parameter.For example, the output constraints 352 may include a minimum torque, amaximum torque, a minimum CA50 and a maximum CA50, a minimum COV of IMEPand a maximum COV of IMEP, a minimum residual dilution and a maximumresidual dilution, and a minimum external dilution and a maximumexternal dilution.

The output constraint module 364 may generally set the outputconstraints 352 to predetermined ranges for the associated predictedparameters, respectively. However, the output constraint module 364 mayvary one or more of the output constraints 352 under some circumstances.For example, the output constraint module 364 may retard the maximumCA50, such as when knock occurs within the engine 102. For anotherexample, the output constraint module 364 may increase the maximum COVof IMEP under low load conditions, such as during engine idling wherethe a higher COV of IMEP may be needed to achieve a given torquerequest.

A reference module 368 (see FIG. 2) generates the reference values 356for the target values 266-270, respectively. The reference values 356include a reference for each of the target values 266-270. In otherwords, the reference values 356 include a reference wastegate openingarea, a reference throttle opening area, a reference EGR opening area, areference intake cam phaser angle, and a reference exhaust cam phaserangle.

The reference module 368 may determine the reference values 356, forexample, based on the air torque request 265 and/or the base air torquerequest 308. The reference values 356 provide references for setting thetarget values 266-270, respectively. The reference values 356 may beused to determine the cost values for possible sequences, as discussedfurther below. The reference values 356 may also be used for one or moreother reasons, such as by the sequence determination module 316 todetermine possible sequences.

Instead of or in addition to generating sequences of possible targetvalues and determining the cost of each of the sequences, the MPC module312 may identify a sequence of possible target values having the lowestcost using convex optimization techniques. For example, the MPC module312 may determine the target values 266-270 using a quadraticprogramming (QP) solver, such as a Dantzig QP solver. In anotherexample, the MPC module 312 may generate a surface of cost values forthe possible sequences of the target values 266-270 and, based on theslope of the cost surface, identify a sequence of possible target valueshaving the lowest cost. The MPC module 312 may then test that sequenceof possible target values to determine whether that sequence of possibletarget values satisfies the actuator constraints 348 and the outputconstraints 352. If so, the MPC module 312 may set the target values266-270 to the first ones of the N values of that selected possiblesequence, respectively, as discussed above.

If the actuator constraints 348 and/or the output constraints 352 arenot satisfied, the MPC module 312 selects another sequence of possibletarget values with a next lowest cost and tests that sequence ofpossible target values for satisfaction of the actuator constraints 348and the output constraints 352. The process of selecting a sequence andtesting the sequence for satisfaction of the actuator constraints 348and the output constraints 352 may be referred to as an iteration.Multiple iterations may be performed during each control loop.

The MPC module 312 performs iterations until a sequence with the lowestcost that satisfies the actuator constraints 348 and the outputconstraints 352 is identified. In this manner, the MPC module 312selects the sequence of possible target values having the lowest costwhile satisfying the actuator constraints 348 and the output constraints352. If a sequence cannot be identified, the MPC module 312 may indicatethat no solution is available.

The cost module 332 may determine the cost for the possible sequences ofthe target values 266-270 based on relationships between: the predictedtorque and the base air torque request 308; the predicted APC and apredetermined minimum APC; the possible target values and the respectiveactuator constraints 348; the other predicted parameters and therespective output constraints 352; and the possible target values andthe respective reference values 356. The relationships may be weighted,for example, to control the effect that each of the relationships has onthe cost.

For example only, the cost module 332 may determine the cost for apossible sequence of the target values 266-270 based on the followingrelationship:Cost=Σ_(i=1) ^(N)ρε² +∥wT*(TP _(i)−BATR)∥² +∥wA*(APCP _(i)−MinAPC)∥²+∥wTV*(PTTOi−TORef)∥² +∥wWG*(PTWGOi−EGORef)∥² +∥wEGR*(PTEGROi−EGRORef)∥²+∥wIP*(PTICPi−ICPRef)∥² +∥wEP*(PTECPi−ECPRef)∥²,subject to the actuator constraints 348 and the output constraints 352.Cost is the cost for the possible sequence of the target values 266-270,TPi is the predicted torque of the engine 102 for an i-th one of the Ncontrol loops, BATR is the base air torque request 308, and wT is aweighting value associated with the relationship between the predictedtorque and the base air torque request 308. APCPi is a predicted APC forthe i-th one of the N control loops, MinAPC is the predetermined minimumAPC, and wA is a weighting value associated with the relationshipbetween the predicted APC and the predetermined minimum APC.

PTTOi is a possible target throttle opening for the i-th one of the Ncontrol loops, TORef is the reference throttle opening, and wTV is aweighting value associated with the relationship between the possibletarget throttle openings and the reference throttle opening. PTWGOi is apossible target wastegate opening for the i-th one of the N controlloops, WGORef is the reference wastegate opening, and wWG is a weightingvalue associated with the relationship between the possible targetwastegate openings and the reference wastegate opening.

PTEGROi is a possible target EGR opening for the i-th one of the Ncontrol loops, EGRRef is the reference EGR opening, and wEGR is aweighting value associated with the relationship between the possibletarget EGR openings and the reference EGR opening. PTICi is a possibletarget intake cam phaser angle for the i-th one of the N control loops,ICPRef is the reference intake cam phaser angle, and wIP is a weightingvalue associated with the relationship between the possible targetintake cam phaser angle and the reference intake cam phaser angle. PTECiis a possible target exhaust cam phaser angle for the i-th one of the Ncontrol loops, ECPRef is the reference exhaust cam phaser angle, and wEPis a weighting value associated with the relationship between thepossible target exhaust cam phaser angle and the reference exhaust camphaser angle.

ρ is a weighting value associated with satisfaction of the outputconstraints 352. ε is a variable that the cost module 332 may set basedon whether the output constraints 352 will be satisfied. For example,the cost module 332 may increase E when a predicted parameter is greaterthan or less than the corresponding minimum or maximum value (e.g., byat least a predetermined amount). The cost module 332 may set E to zerowhen all of the output constraints 352 are satisfied. ρ may be greaterthan the weighting value wT, the weighting value wA, and the otherweighting values (wTV, wWG, wEGR, wIP, wEP) such that the costdetermined for a possible sequence will be large if one or more of theoutput constraints 352 are not satisfied. This may help preventselection of a possible sequence where one or more of the outputconstraints 352 are not satisfied.

The weighting value wT may be greater than the weighting value wA andthe weighting values wTV, wWG, wEGR, wIP, and wEP. In this manner, therelationship between the relationship between the predicted enginetorque and the base air torque request 308 have a larger effect on thecost and, therefore, the selection of one of the possible sequences asdiscussed further below. The cost increases as the difference betweenthe predicted engine torque and the base air torque request 308increases and vice versa.

The weighting value wA may be less than the weighting value wT andgreater than the weighting values wTV, wWG, wEGR, wIP, and wEP. In thismanner, the relationship between the predicted APC and zero has a largeeffect on the cost, but less than the relationship between the predictedengine torque and the base air torque request 308. The cost increases asthe difference between the predicted APC and the predetermined minimumAPC increases and vice versa. For example only, the predeterminedminimum APC may be zero or another suitable value.

Determining the cost based on the difference between the predicted APCand the predetermined minimum APC helps ensure that the APC will beminimized. Decreasing APC decreases fuel consumption as fueling iscontrolled based on the actual APC to achieve a target air/fuel mixture.As the selection module 344 may select the one of the possible sequenceshaving the lowest cost, the selection module 344 may select the one ofthe possible sequences that best achieves the base air torque request308 while minimizing the APC. While the example of minimizing APC isdiscussed, in various implementations, an efficiency parameter may bepredicted and maximized. For example, the efficiency parameter may bepredicted torque divided by predicted APC.

The weighting values wTV, wWG, wEGR, wIP, and wEP may be less than allof the other weighting values. In this manner, during steady-stateoperation, the target values 266-270 may settle near or at the referencevalues 356, respectively. During transient operation, however, the MPCmodule 312 may adjust the target values 266-270 away from the referencevalues 356 in order to achieve the base air torque request 308, whileminimizing the APC and satisfying the actuator constraints 348 and theoutput constraints 352.

Referring now to FIG. 4, a flowchart depicting an example method ofcontrolling the throttle valve 112, the intake cam phaser 148, theexhaust cam phaser 150, the wastegate 162 (and therefore theturbocharger), and the EGR valve 170 using MPC (model predictivecontrol) is presented. Control may begin with 404 where the torquerequesting module 224 determines the air torque request 265 based on theadjusted predicted and immediate torque requests 263 and 264.

At 408, the torque conversion module 304 may convert the air torquerequest 265 into the base air torque request 308 or into anothersuitable type of torque for use by the MPC module 312. The sequencedetermination module 316 determines possible sequences of the targetvalues 266-270 based on the base air torque request 308 at 412.

At 416, the prediction module 323 determines the predicted parametersfor each of the possible sequences of target values. The predictionmodule 323 determines the predicted parameters for the possiblesequences based on the model 324 of the engine 102, the exogenous inputs328, and the feedback inputs 330. More specifically, based on a possiblesequence of the target values 266-270, the exogenous inputs 328, and thefeedback inputs 330, using the model 324, the prediction module 323generates a sequence of predicted torques of the engine 102 for the Ncontrol loops, a sequence of predicted APCs for the N control loops, asequence of predicted amounts of external dilution for the N controlloops, a sequence of predicted amounts of residual dilution for the Ncontrol loops, a sequence of predicted combustion phasing values for theN control loops, and a sequence of predicted combustion quality valuesfor the N control loops.

The cost module 332 determines the costs for the possible sequences,respectively, at 420. For example only, the cost module 332 maydetermine the cost for a possible sequence of the target values 266-270based on the equationCost=Σ_(i=1) ^(N)ρε² +∥wT*(TP_(i)−BATR)∥² +∥wA*(APCP _(i)−MinAPC)∥²+∥wTV*(PTTOi−TORef)∥² +∥wWG*(PTWGOi−EGORef)∥² +∥wEGR*(PTEGROi−EGRORef)∥²+∥wIP*(PTICPi−ICPRef)∥² +∥wEP*(PTECPi−ECPRef)∥²,subject to the actuator constraints 348 and the output constraints 352,as discussed above.

The selection module 344 selects one of the possible sequences of thetarget values 266-270 based on the costs of the possible sequences,respectively, at 424. For example, the selection module 344 may selectthe one of the possible sequences having the lowest cost. The selectionmodule 344 may therefore select the one of the possible sequences thatbest achieves the base air torque request 308 while minimizing the APC.Instead of or in addition to determining possible sequences of thetarget values 230-244 at 412 and determining the cost of each of thesequences at 420, the MPC module 312 may identify a sequence of possibletarget values having the lowest cost using convex optimizationtechniques as discussed above.

The MPC module 312 may determine whether the selected one of thepossible sequences satisfies the actuator constraints 348 at 425. If 425is true, control may continue with 428. If 425 is false, the MPC module312 may determine, based on the selected possible sequence, a possiblesequence that satisfies the actuator constraints 348 and that has thelowest cost at 426, and control may continue with 428. The possiblesequence that satisfies the actuator constraints 348 and that has thelowest cost may be used, as discussed below.

At 428, the first conversion module 272 converts the target wastegateopening area 266 into the target duty cycle 274 to be applied to thewastegate 162, the second conversion module 276 converts the targetthrottle opening area 267 into the target duty cycle 278 to be appliedto the throttle valve 112. The third conversion module 280 also convertsthe target EGR opening area 268 into the target duty cycle 282 to beapplied to the EGR valve 170 at 428. The fourth conversion module mayalso convert the target intake and exhaust cam phaser angles 269 and 270into the target intake and exhaust duty cycles to be applied to theintake and exhaust cam phasers 148 and 150, respectively.

At 432, the throttle actuator module 116 controls the throttle valve 112to achieve the target throttle opening area 267, and the phaser actuatormodule 158 controls the intake and exhaust cam phasers 148 and 150 toachieve the target intake and exhaust cam phaser angles 269 and 270,respectively. For example, the throttle actuator module 116 may apply asignal to the throttle valve 112 at the target duty cycle 278 to achievethe target throttle opening area 267.

Also at 432, the EGR actuator module 172 controls the EGR valve 170 toachieve the target EGR opening area 268, and the boost actuator module164 controls the wastegate 162 to achieve the target wastegate openingarea 266. For example, the EGR actuator module 172 may apply a signal tothe EGR valve 170 at the target duty cycle 282 to achieve the target EGRopening area 268, and the boost actuator module 164 may apply a signalto the wastegate 162 at the target duty cycle 274 to achieve the targetwastegate opening area 266. While FIG. 4 is shown as ending after 432,FIG. 4 may be illustrative of one control loop, and control loops may beexecuted at a predetermined rate.

Referring back to FIG. 3, a fault diagnostic module 380 may monitor theMPC module 312 and diagnose the presence of one or more faults in theMPC module 312. The fault diagnostic module 380 generates a fault signal384 when one or more faults are present in the MPC module 312. Aswitching module 388 may set the target values 266-270 to those set bythe MPC module 312 when the fault signal 384 is not generated.

When the fault signal 384 is generated, the switching module 388 setsthe target values 266-270 to the reference values 356, respectively.More specifically, the switching module 388 may set the target wastegateopening area 266 to the reference wastegate opening area, the targetthrottle opening area 267 to the reference throttle opening area, thetarget EGR opening area 268 to the reference EGR opening area, thetarget intake cam phaser angle 269 to the reference intake cam phaserangle, and the target exhaust cam phaser angle 270 to the referenceexhaust cam phaser angle. Changes in the target values 266-270 may berate limited.

The fault diagnostic module 380 may monitor the integrator values andcompare the integrator values with respective predetermined values. Whenan integrator value is greater than the respective predetermined value,the fault diagnostic module 380 may determine whether the integratorvalue would be less than the respective predetermined value if adifferent set of the A, B, and C matrices was used.

For example, the fault diagnostic module 380 may determine a nextclosest set of the A, B, and C matrices to the current operatingconditions. The fault diagnostic module 380 may determine the integratorvalues based on that set of the A, B, and C matrices. The faultdiagnostic module 380 may determine whether the integrator valuesdetermined based on that set of the A, B, and C matrices are less thanthe respective predetermined values. If so, the fault diagnostic module380 may command the prediction module 323 to use that set of the A, B,and C matrices.

The fault diagnostic module 380 may diagnose a fault in the MPC module312 when at least a predetermined number of the integrator values aregreater than the predetermined values, respectively. The predeterminednumber is an integer greater than 1 and less than or equal to the numberof predicted parameters.

The fault diagnostic module 380 may also diagnose a fault in the MPCmodule 312 when the MPC module 312 indicates that no solution isavailable to a given set of inputs. The fault diagnostic module 380 mayalso diagnose a fault in the MPC module 312 when one or more of thetarget values 266-270 set by the MPC module 312 is outside of one ormore of the respective actuator constraints 348.

The fault diagnostic module 380 may also diagnose a fault in the MPCmodule 312 when the cost determined for a sequence selected and testedduring one iteration is less than the cost determined for a sequenceselected and tested during a previous iteration of a control loop. Asdiscussed above, the MPC module 312 the cost of the selected sequencesshould increase (or at least stay the same) from iteration to iterationduring a control loop. Thus, a decrease in the cost of selectedsequences from iteration to iteration of a control loop may beindicative of a fault in the MPC module 312.

The fault diagnostic module 380 may also diagnose a fault in the MPCmodule 312 when, for two or more different control loops, more than apredetermined maximum number of iterations have been performed to selectthe sequence of target values for use. As discussed above, multipleiterations may be performed during a control loop to identify a possiblesequence of the target values for use. The possible sequence may beidentified too late for use during the current control loop, however,when more than the predetermined maximum number of iterations areperformed in order to select that possible sequence. Performing morethan the predetermined maximum number of iterations for two or morecontrol loops during a predetermined number of control loops mayindicate a fault in the MPC module 312.

As discussed above, the fault diagnostic module 380 generates the faultsignal 384 when one or more faults are diagnosed in the MPC module 312.The fault diagnostic module 380 may take one or more other actions whenone or more faults are diagnosed in the MPC module 312.

For example, the fault diagnostic module 380 may perform one or moretests on the MPC module 312 when one or more faults are diagnosed in theMPC module 312. The fault diagnostic module 380 may provide a firstpredetermined set of inputs to the prediction module 323 for a firsttest of the MPC module 312. The first predetermined set of inputs mayinclude, for example, A, B, and C matrices to use, predetermined valuesfor the vector x(k), and predetermined values for the vector u(k). Theprediction module 323 generates the vector x(k+1) and the vector y(k)based on the first predetermined set of inputs.

The fault diagnostic module 380 may determine that the MPC module 312passed the first test when the values of the vectors x(k+1) and y(k)generated based on the first predetermined set of inputs are the same aspredetermined expected values, respectively. The fault diagnostic module380 may determine that the MPC module 312 failed the first test when oneor more of the values of the vectors x(k+1) and y(k) generated based onthe first predetermined set of inputs are different than thepredetermined expected values, respectively.

The fault diagnostic module 380 may set the values of the vector x(k) topredetermined initialization values for a second test of the MPC module312. The fault diagnostic module 380 may then monitor the integratorvalues to determine whether the integrator values are less than therespective predetermined values.

The fault diagnostic module 380 may determine that the second testpassed when the integrator values are less than the respectivepredetermined values after the values of the vector x(k) are set to thepredetermined initialization values. The fault diagnostic module 380 maydetermine that the second test failed when one or more of the integratorvalues remain greater than the respective predetermined values for apredetermined period after the values of the vector x(k) are set to thepredetermined initialization values.

The fault diagnostic module 380 may provide a second predetermined setof inputs to the MPC module 312 for a third test. The secondpredetermined set of inputs may include a predetermined base air torquerequest, predetermined reference values, predetermined exogenous andfeedback inputs, predetermined output constraints, and predeterminedactuator constraints. The second predetermined set of inputs may alsoinclude other predetermined values for other parameters that are used bythe MPC module 312 to set the target values 266-270. The MPC module 312is expected to set the target values 266-270 to predetermined values,respectively, based on the second predetermined set of inputs.

The fault diagnostic module 380 may determine that the MPC module 312passed the third test when the target values 266-270 set based on thesecond predetermined set of inputs are the same as the respectivepredetermined values. The fault diagnostic module 380 may determine thatthe MPC module 312 failed the third test when one or more of the targetvalues 266-270 are different than the respective predetermined values.

When all of the tests have passed, the fault diagnostic module 380 maystop generating the fault signal 384. The switching module 388 may thenselect the target values set by the MPC module 312 for use. When one ormore of the tests have failed, the fault diagnostic module 380 maycontinue to generate the fault signal 384 to continue the use of thereference values 356. When one or more of the tests have failed for apredetermined period, the fault diagnostic module 380 may set apredetermined diagnostic trouble code (DTC) in memory, illuminate amalfunction indicator lamp (not shown), and/or take one or more otherremedial actions.

Referring now to FIG. 5, a flowchart depicting an example method ofdiagnosing faults in the MPC module 312. Control may begin with 504where the fault diagnostic module 380 determines whether an integratorvalue is greater than the respective predetermined value. As describedabove, the MPC module 312 includes an integrator determines theintegrator value based on differences between predicted values of aparameter and estimated or measured values of that parameter. If 504 istrue, control continues with 508. If 504 is false, control may continuewith 528, which is discussed further below.

At 508, the fault diagnostic module 380 determines whether theintegrator value would be less than the respective predetermined valueif another set of the A, B, and C matrices was used to determine thepredicted parameter used to determine the integrator value. If 508 istrue, the fault diagnostic module 380 may command the MPC module 312 touse that set of the A, B, and C matrices at 512, and control continueswith 516. If 508 is false, control may continue with 528.

At 516, the fault diagnostic module 380 determines whether two or moreof the integrator values are greater than the respective predeterminedvalues. If 516 is true, the fault diagnostic module 380 generates thefault signal 384 to indicate that a fault is present in the MPC module312 at 524. In response to the generation of the fault signal 384, theswitching module 388 selects the reference values 356 for use as thetarget values 266-270, respectively, at 524. In various implementations,516 may be performed before 512, such as after 504 and before 508, orafter 508 and before 512. In such an implementation, control may endafter 512.

The fault diagnostic module 380 determines whether the cost determinedfor the selected sequence decreases from one iteration to a lateriteration at 528. If 528 is true, the fault diagnostic module 380generates the fault signal 384 to indicate that a fault is present inthe MPC module 312, and the reference values 356 are used at 524. If 528is false, control may continue with 532.

At 532, the fault diagnostic module 380 determines whether the MPCmodule 312 has indicated that no solution is available for setting thetarget values 266-270. If 532 is true, the fault diagnostic module 380generates the fault signal 384 to indicate that a fault is present inthe MPC module 312, and the reference values 356 are used at 524. If 532is false, control may continue with 536.

The fault diagnostic module 380 determines whether one or more of thetarget values 266-270 set by the MPC module 312 are outside of one ormore of the actuator constraints 348 at 536. If 536 is true, the faultdiagnostic module 380 generates the fault signal 384 to indicate that afault is present in the MPC module 312, and the reference values 356 areused at 524. If 536 is false, control may continue with 540.

At 540, the fault diagnostic module 380 may determine whether more thanthe predetermined maximum number of iterations were performed by the MPCmodule 312 to select one of the possible sequences for at least thepredetermined number of control loops. If 540 is true, the faultdiagnostic module 380 generates the fault signal 384 to indicate that afault is present in the MPC module 312, and the reference values 356 areused at 524. If 540 is false, control may end. While FIG. 5 is shown asending after 524 or 540, FIG. 5 may be illustrative of one control loop,and control loops may be executed at a predetermined rate. Thispredetermined rate may be the same or different than the predeterminedrate of the control loops of FIG. 4.

Referring now to FIG. 6, a flowchart depicting an example method oftesting the MPC module 312 is presented. Control may begin with 604where the fault diagnostic module 380 determines whether one or morefaults are present in the MPC module 312. If 604 is true, controlcontinues with 608. If 604 is false, control may remain at 604.Discussion of diagnosing faults in the MPC module 312 is discussedabove.

At 608, the fault diagnostic module 380 provides the first predeterminedset of inputs to the prediction module 323 for the first test of the MPCmodule 312. The prediction module 323 generates the vector x(k+1) andthe vector y(k) based on the first predetermined set of inputs.

At 612, the fault diagnostic module 380 determines whether the values ofthe vectors x(k+1) and y(k) generated by the MPC module 312 based on thefirst predetermined set of inputs are the same as the predeterminedexpected values, respectively. If 612 is true, the fault diagnosticmodule 380 may determine that the MPC module 312 has passed the firsttest, and control may continue with 616. If 612 is false, the faultdiagnostic module 380 may determine that the MPC module 312 failed thefirst test, and control may continue with 636, which is discussedfurther below.

At 616, the fault diagnostic module 380 may command the predictionmodule 323 to set the values of the vector x(k) to the predeterminedinitialization values for the second test. At 620, the fault diagnosticmodule 380 monitors the integrator values and determines whether theintegrator values become less than the respective predetermined values.If 620 is true, the fault diagnostic module 380 may determine that theMPC module 312 has passed the second test, and control may continue with624. If 620 is false, the fault diagnostic module 380 may determine thatthe MPC module 312 failed the second test, and control may continue with636.

The fault diagnostic module 380 provides the second predetermined set ofinputs to the MPC module 312 at 624. Based on the second predeterminedset of inputs, the MPC module 312 selects one of the possible sequencesof target values and generates a set of target values based on the firstone of each of the target values of the selected possible sequence.

At 628, the fault diagnostic module 380 determines whether the targetvalues set by the MPC module 312 based on the second predetermined setof inputs are the same as predetermined expected values, respectively.If 628 is true, the fault diagnostic module 380 may determine that theMPC module 312 has passed the third test, and control may continue with632. If 628 is false, the fault diagnostic module 380 may determine thatthe MPC module 312 failed the third test, and control may continue with636.

At 632, when the fault diagnostic module 380 has determined that all ofthe tests have passed, the fault diagnostic module 380 may determinethat no fault is present in the MPC module 312 and disable generation ofthe fault signal 384. The switching module 388 then uses the targetvalues set by the MPC module 312.

At 636, when the fault diagnostic module 380 has determined that one ormore of the tests have failed, the fault diagnostic module 380 maydetermine that one or more faults are present in the MPC module 312 andcontinue to generate the fault signal 384. As such, the switching module388 continues to use the reference values 356 to control the respectiveactuators.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A or Bor C), using a non-exclusive logical OR. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.

In this application, including the definitions below, the term modulemay be replaced with the term circuit. The term module may refer to, bepart of, or include an Application Specific Integrated Circuit (ASIC); adigital, analog, or mixed analog/digital discrete circuit; a digital,analog, or mixed analog/digital integrated circuit; a combinationallogic circuit; a field programmable gate array (FPGA); a processor(shared, dedicated, or group) that executes code; memory (shared,dedicated, or group) that stores code executed by a processor; othersuitable hardware components that provide the described functionality;or a combination of some or all of the above, such as in asystem-on-chip.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared processor encompasses a single processorthat executes some or all code from multiple modules. The term groupprocessor encompasses a processor that, in combination with additionalprocessors, executes some or all code from one or more modules. The termshared memory encompasses a single memory that stores some or all codefrom multiple modules. The term group memory encompasses a memory that,in combination with additional memories, stores some or all code fromone or more modules. The term memory may be a subset of the termcomputer-readable medium. The term computer-readable medium does notencompass transitory electrical and electromagnetic signals propagatingthrough a medium, and may therefore be considered tangible andnon-transitory. Non-limiting examples of a non-transitory tangiblecomputer readable medium include nonvolatile memory, volatile memory,magnetic storage, and optical storage.

The apparatuses and methods described in this application may bepartially or fully implemented by one or more computer programs executedby one or more processors. The computer programs includeprocessor-executable instructions that are stored on at least onenon-transitory tangible computer readable medium. The computer programsmay also include and/or rely on stored data.

What is claimed is:
 1. An engine control system for a vehicle,comprising: a model predictive control (MPC) module that: identifiessets of possible target values based on an engine torque request;determines predicted operating parameters for the sets of possibletarget values, respectively; determines cost values for the sets ofpossible target values, respectively; selects one of the sets ofpossible target values based on the cost values; and sets target valuesbased on the possible target values of the selected one of the sets; anactuator module that controls an engine actuator based on one of thetarget values; and a fault diagnostic module that selectively diagnosesa fault in the MPC module.
 2. The engine control system of claim 1wherein the MPC module selects one of the sets of possible target valuesfurther based on predetermined ranges for the target values,respectively.
 3. The engine control system of claim 2 wherein the faultdiagnostic module diagnoses the fault when one of the target values isoutside of its predetermined range.
 4. The engine control system ofclaim 2 wherein the MPC module: identifies a first one of the sets ofpossible target values based on a first cost value of the first one ofthe sets; determines whether the possible target values of the first oneof the possible sets are within the predetermined ranges, respectively;when one of the possible target values of the selected one of the setsis outside of its predetermined range, identifies a second one of thesets of possible target values based on a second cost value of thesecond one of the sets; and, when the possible target values of thesecond one of the sets are within the predetermined ranges,respectively, selects the second one of the sets.
 5. The engine controlsystem of claim 4 wherein the fault diagnostic module diagnoses thefault when the second cost value of the second one of the sets is lessthan the first cost value of the first one of the sets.
 6. The enginecontrol system of claim 2 wherein the fault diagnostic module diagnosesthe fault in the MPC module when the MPC module fails to select one ofthe sets of possible target values within a predetermined period.
 7. Theengine control system of claim 1 wherein the MPC module furtherdetermines an integrator value based on a difference between a first oneof the predicted operating parameters and one of a measured and anestimated value of that operating parameter.
 8. The engine controlsystem of claim 7 wherein the fault diagnostic module diagnoses thefault in the MPC module when the integrator value is greater than apredetermined value.
 9. The engine control system of claim 1 furthercomprising: a reference module that determines reference values based onthe engine torque request, wherein, when the fault is diagnosed in theMPC module, the actuator module controls the engine actuator based onone of the reference values.
 10. The engine control system of claim 1further comprising: a boost actuator module that controls opening of awastegate of a turbocharger based on a second one of the target values;an exhaust gas recirculation (EGR) actuator module that controls openingof an EGR valve based on a third one of the target values; and a phaseractuator module that controls intake and exhaust valve phasing based onfourth and fifth ones of the target values, respectively, wherein theactuator module controls the opening of a throttle valve based on theone of the target values.
 11. An engine control method for a vehicle,comprising: using a model predictive control (MPC) module: identifyingsets of possible target values based on an engine torque request;determining predicted operating parameters for the sets of possibletarget values, respectively; determining cost values for the sets ofpossible target values, respectively; selecting one of the sets ofpossible target values based on the cost values; and setting targetvalues based on the possible target values of the selected one of thesets; controlling an engine actuator based on one of the target values;and selectively diagnosing a fault in the MPC module.
 12. The enginecontrol method of claim 11 further comprising selecting one of the setsof possible target values further based on predetermined ranges for thetarget values, respectively.
 13. The engine control method of claim 12further comprising diagnosing the fault when one of the target values isoutside of its predetermined range.
 14. The engine control method ofclaim 12 further comprising: using the MPC module: identifying a firstone of the sets of possible target values based on a first cost value ofthe first one of the sets; determining whether the possible targetvalues of the first one of the possible sets are within thepredetermined ranges, respectively; when one of the possible targetvalues of the selected one of the sets is outside of its predeterminedrange, identifying a second one of the sets of possible target valuesbased on a second cost value of the second one of the sets; and, whenthe possible target values of the second one of the sets are within thepredetermined ranges, respectively, selecting the second one of thesets.
 15. The engine control method of claim 14 further comprisingdiagnosing the fault when the second cost value of the second one of thesets is less than the first cost value of the first one of the sets. 16.The engine control method of claim 12 further comprising diagnosing thefault in the MPC module when the MPC module fails to select one of thesets of possible target values within a predetermined period.
 17. Theengine control method of claim 11 further comprising determining anintegrator value based on a difference between a first one of thepredicted operating parameters and one of a measured and an estimatedvalue of that operating parameter.
 18. The engine control method ofclaim 17 further comprising diagnosing the fault in the MPC module whenthe integrator value is greater than a predetermined value.
 19. Theengine control method of claim 11 further comprising: determiningreference values based on the engine torque request; and, when the faultis diagnosed in the MPC module, controlling the engine actuator based onone of the reference values.
 20. The engine control method of claim 11further comprising: controlling opening of a wastegate of a turbochargerbased on a second one of the target values; controlling opening of anexhaust gas recirculation (EGR) valve based on a third one of the targetvalues; and controlling intake and exhaust valve phasing based on fourthand fifth ones of the target values, respectively, wherein the engineactuator is a throttle valve.